Those “new” tires of yours could be six-years old and ready to disintegrate on the highway. Tire rubber dries out after six years, but unlike in Europe and Asia, American companies are allowed to sell expired tires long after they turn into death donuts. A 20/20 investigation found that the “new” tires on sale at Sears and Walmart can be up to 12-years-old. Inside, how to tell when your tires were born…